A typical prior art electrical connection box is shown in FIGS. 11 and 12 hereof. As can be seen therefrom, insertion groove 42 is formed on the outer surface of main housing 41. Busbar 43 is inserted into main housing 41 through insertion groove 42. Cylindrical connector holder 44 projects from an outer face of main housing 41. Slits 45 are formed on either side wall of connector holder 44 so as to be contiguous with insertion groove 42. Connection terminal 46 projects from busbar 43 into connector holder 44.
Connector 47 is removably attached to connector holder 44 and is adapted to mate with connection terminal 48, which is disposed in the connector holder. Engagement claw 49 projects from the inner surface of the perimeter wall of connector holder 44 and engagement projection 50 projects from the outer surface of connector 47 so that it can be engaged by the engagement claw. This engagement holds and provides support for connector 47 and connector holder 44 in their affixed position.
Busbar 43 is connected to a power supply (not shown) via wire harness 51 and the connection between contact terminal 46 and connection terminal 48. Thereafter, the current is distributed to the various electrical elements.
In the foregoing electrical connection box, slit 45 is formed in the perimeter wall of connector holder 44 and located so as to be contiguous with insertion groove 42 of main housing 41. The busbar is inserted into the housing via this insertion groove and through the slit. Thus, when connector unit 47 is inserted into connector holder 44, as shown in FIG. 12, the perimeter wall of connector holder 44 causes slit 45 to expand. As a result, connector 47 can tilt and even cause disengagement of engagement projection 50 from claw 49. This could permit connector 47 to fall out of connector holder 44. It is an object of the present Invention to overcome the foregoing problem and to thereby provide an electrical connection box which prevents the connector unit from expanding the slit and from tilting or falling out of the connector holder.